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Honors Chemistry: Unit 1 Vocabulary

Terms in this set (48)

chemistry
the study of the composition, structure, and properties of matter and the changes it undergoes
matter
anything that has mass and volume
chemical
any substance that has a definite composition
physical properties
a characteristic of a substance that does not involve a chemical change (can be determined without changing the nature of the substance)
examples of physical properties
color, state, melting point, boiling point
chemical properties
a property of matter that a substance's ability to participate in chemical reactions (can only be identified by trying to cause a chemical change)
examples of chemical properties
reactivity, burning, melting
physical changes
changes in which the identity of a substance does not change
evaporation
the change of state from liquid to gas
-energy is required to separate liquid particles, they gain energy when they collide
-if a particle gains a lot of energy, it can leave the liquids surface and join gas particles
condensation
the change of state from gas to a liquid
-when gas particles no longer have enough energy to overcome the attractive forces between them, they turn into a liquid
melting
the change of state from solid to liquid
-as a solid is heated, the particles vibrate faster in their fixed positions, at a certain temp, the molecules can have enough energy to break out of the fixed positions
freezing
the change of state from liquid to solid
-as a liquid is cooled, the movement of particles becomes slower. at a certain temp, the particles are pulled together into the fixed positions of a solid
sublimation
the change of state from solid to gas
-the particles in a solid re constantly vibrating, some particles have higher energy, these particles with high enough energy an escape the solid
depostion
the change of state from a gas to a solid
-molecules in the gaseous state become part of the surface of a crystal
chemical changes
the identities of substances change and new substances form
chemical reactions
the process by which one or more substances change to produce one or new more substances
reactants
a substance or molecule that participates in a chemical reaction (they are used up in a chemical reaction)
products
a substance that forms in a chemical reaction (they are made in a chemical reaction)
atom
the smallest unit of an element that maintains the properties of that element
pure substance
a sample of matter, either a single element or a single compound, that has definite chemical and physical properties
element
pure substances that contain only one type of atom
molecule
the smallest unit of a substance that keeps all of the physical and chemical properties of that substance
compound
a substance made up of atoms of two or more different elements joined by chemical bonds
mixture
a combination of two or more substances that are not chemically combined
homogeneous mixture
something that has uniform structure or composition throughout
examples of homogeneous mixtures
gasoline, syrup, air
heterogeneous mixture
composed of dissimilar compounds
examples of heterogeneous mixtures
a mixture of sand and water
energy
the capacity to do some kind of work, such as moving an object, forming a new compound, or generating light
endothermic
a process in which energy is absorbed by the system from the surroundings
exothermic
a process in which a system releases energy into the surroundings
law of conservation of energy
energy cannot be created of destroyed but can change from one form to another
heat
the energy transferred between objects that are at different temperatures
temperature
a measurement of the average kinetic energy of the random motion of particles in a substance
specific heat
the quantity of energy as heat requires to raise the temperature of 1 g of a substance 1 k
kelvin
celcius + 273.15
celcius
kelvin - 273.15
types of exothermic energy
freezing, deposition, condensation
types of endothermic energy
melting, evaporation, sublimation
main parts of the scientific method
collecting data, forming a hypothesis, test the hypothesis, stating conclusions
theory
a well tested explanation of observations
law
a statement or mathematical expression that describes a behavior of the natural world
solid
particles are tightly packed together
liquid
molecules are loosley packed
gas
molecules re roaming everywhere in no pattern
movement of particles in a solid
they vibrate slightly
movement of particles in a liquid
they are not held together so they can slip past each other
movement of particles in a gas
molecules move independently at a high speed
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